/*
 * Copyright (c) 2007-2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: Arg.java,v 1.1.2.1 2005/08/01 01:30:11 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal;

import com.sun.org.apache.xml.internal.utils.QName;
import com.sun.org.apache.xpath.internal.objects.XObject;
import java.util.Objects;

/**
 * This class holds an instance of an argument on
 * the stack. The value of the argument can be either an
 * XObject or a String containing an expression.
 * @xsl.usage internal
 */
public class Arg {

    /** Field m_qname: The name of this argument, expressed as a QName
     * (Qualified Name) object.
     * @see getQName
     * @see setQName
     *  */
    private QName m_qname;

    /**
     * Get the qualified name for this argument.
     *
     * @return QName object containing the qualified name
     */
    public final QName getQName() {
        return m_qname;
    }

    /**
     * Set the qualified name for this argument.
     *
     * @param name QName object representing the new Qualified Name.
     */
    public final void setQName(QName name) {
        m_qname = name;
    }

    /** Field m_val: Stored XObject value of this argument
     * @see #getVal()
     * @see #setVal()
     */
    private XObject m_val;

    /**
     * Get the value for this argument.
     *
     * @return the argument's stored XObject value.
     * @see #setVal(XObject)
     */
    public final XObject getVal() {
        return m_val;
    }

    /**
     * Set the value of this argument.
     *
     * @param val an XObject representing the arguments's value.
     * @see #getVal()
     */
    public final void setVal(XObject val) {
        m_val = val;
    }

    /**
     * Have the object release it's resources.
     * Call only when the variable or argument is going out of scope.
     */
    public void detach() {
        if (null != m_val) {
            m_val.allowDetachToRelease(true);
            m_val.detach();
        }
    }

    /** Field m_expression: Stored expression value of this argument.
     * @see #setExpression
     * @see #getExpression
     * */
    private String m_expression;

    /**
     * Get the value expression for this argument.
     *
     * @return String containing the expression previously stored into this
     * argument
     * @see #setExpression
     */
    public String getExpression() {
        return m_expression;
    }

    /**
     * Set the value expression for this argument.
     *
     * @param expr String containing the expression to be stored as this
     * argument's value.
     * @see #getExpression
     */
    public void setExpression(String expr) {
        m_expression = expr;
    }

    /**
     * True if this variable was added with an xsl:with-param or
     * is added via setParameter.
     */
    private boolean m_isFromWithParam;

    /**
     * Tell if this variable is a parameter passed with a with-param or as
     * a top-level parameter.
     */
    public boolean isFromWithParam() {
        return m_isFromWithParam;
    }

    /**
     * True if this variable is currently visible.  To be visible,
     * a variable needs to come either from xsl:variable or be
     * a "received" parameter, ie one for which an xsl:param has
     * been encountered.
     * Set at the time the object is constructed and updated as needed.
     */
    private boolean m_isVisible;

    /**
     * Tell if this variable is currently visible.
     */
    public boolean isVisible() {
        return m_isVisible;
    }

    /**
     * Update visibility status of this variable.
     */
    public void setIsVisible(boolean b) {
        m_isVisible = b;
    }

    /**
     * Construct a dummy parameter argument, with no QName and no
     * value (either expression string or value XObject). isVisible
     * defaults to true.
     */
    public Arg() {

        m_qname = new QName("");
        // so that string compares can be done.
        m_val = null;
        m_expression = null;
        m_isVisible = true;
        m_isFromWithParam = false;
    }

    /**
     * Construct a parameter argument that contains an expression.
     *
     * @param qname Name of the argument, expressed as a QName object.
     * @param expression String to be stored as this argument's value expression.
     * @param isFromWithParam True if this is a parameter variable.
     */
    public Arg(QName qname, String expression, boolean isFromWithParam) {

        m_qname = qname;
        m_val = null;
        m_expression = expression;
        m_isFromWithParam = isFromWithParam;
        m_isVisible = !isFromWithParam;
    }

    /**
     * Construct a parameter argument which has an XObject value.
     * isVisible defaults to true.
     *
     * @param qname Name of the argument, expressed as a QName object.
     * @param val Value of the argument, expressed as an XObject
     */
    public Arg(QName qname, XObject val) {

        m_qname = qname;
        m_val = val;
        m_isVisible = true;
        m_isFromWithParam = false;
        m_expression = null;
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(this.m_qname);
    }

    /**
     * Equality function specialized for the variable name.  If the argument
     * is not a qname, it will deligate to the super class.
     *
     * @param   obj   the reference object with which to compare.
     * @return  <code>true</code> if this object is the same as the obj
     *          argument; <code>false</code> otherwise.
     */
    @Override
    public boolean equals(Object obj) {
        if (obj instanceof QName) {
            return m_qname.equals(obj);
        } else
            return super.equals(obj);
    }

    /**
     * Construct a parameter argument.
     *
     * @param qname Name of the argument, expressed as a QName object.
     * @param val Value of the argument, expressed as an XObject
     * @param isFromWithParam True if this is a parameter variable.
     */
    public Arg(QName qname, XObject val, boolean isFromWithParam) {

        m_qname = qname;
        m_val = val;
        m_isFromWithParam = isFromWithParam;
        m_isVisible = !isFromWithParam;
        m_expression = null;
    }
}
